31/3-3
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General information
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Wellbore history
GeneralThe wildcat well 31/3-3 was drilled on a structure east of the Troll Field. The structure, which is deeper than the oil/water contact proved in the Troll Field area, is defined on the Top Sognefjord Formation and situated on a rotated fault block compartment dipping gently to the east. The main objective of the well was to test the Late Jurassic sandstones, which were gas and oil bearing in the Troll Field. A possible stratigraphic trap in the Early Cretaceous sequence and small closures of the Brent Group and Statfjord Formation were secondary targets.Operations and resultsWell 31/3-3 was spudded with the semi-submersible installation Treasure Saga on 13 October 1984 and drilled to TD at 2573 m in the Early Jurassic Statfjord Formation. No major problems occurred due to drilling. The well was drilled using spud mud down to 406 m, with KCl/polymer from 406 m to 1630 m, with CaCO3 mud from 1630 m to 2112 m, and with gel/lignosulphonate from 2112 m to TD.No reservoir rock was encountered in the Early Cretaceous. In the Jurassic a 152 m thick sequence of Sognefjord Formation consisting of several stacked coarsening upward sand sequences was penetrated. The Statfjord Formation consisted of alternating sandstones and claystones with traces of limestone, mica and coal fragments. The only trace of hydrocarbons in the well were two very weak shows, possibly dope contamination, in cores no 3 and 5 in the Sognefjord Formation. Seven conventional cores were cut, one in the lower part of the Cromer Knoll Group and the last six in the Late Jurassic Sognefjord and Heather Formations. Totally 168.5 m were cut with a recovery of 166.5 m (99%). No fluid samples were taken.The well was permanently abandoned on 18 November 1984 as a dry well.TestingNo drill stem test was performed -
Cuttings at the Norwegian Offshore Directorate
Cuttings at the Norwegian Offshore Directorate Cuttings available for sampling?YESCuttings at the Norwegian Offshore Directorate Cutting sample, top depth [m]Cutting samples, bottom depth [m]490.002573.00 -
Cores at the Norwegian Offshore Directorate
Cores at the Norwegian Offshore Directorate Core sample numberCore sample - top depthCore sample - bottom depthCore sample depth - uom11580.01596.0[m ]21764.01782.0[m ]31782.01810.0[m ]41810.01837.5[m ]51837.51858.9[m ]61861.01888.5[m ]71888.51916.5[m ]Cores at the Norwegian Offshore Directorate Total core sample length [m]166.4Cores at the Norwegian Offshore Directorate Cores available for sampling?YES -
Core photos
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Casing and leak–off tests
Casing and leak–off tests Casing typeCasing diam.
[inch]Casing depth
[m]Hole diam.
[inch]Hole depth
[m]LOT/FIT mud eqv.
[g/cm3]Formation test typeCONDUCTOR30481.036486.00.00LOTSURF.COND.20805.0261143.01.60LOTINTERM.13 3/81616.017 1/21764.01.54LOTOPEN HOLE2573.012 1/42573.00.00LOT -
Logs
Logs Log typeLog top depth [m]Log bottom depth [m]CALIPER566632CDL CNL GR8041632CDL CNL GR16142571DIFL LSBHC GR481815DIFL LSBHC GR8041632DIFL LSBHC GR16142573DIPLOG16222573FMT17752493GR332481SPECTRALOG16142566SWC15801596SWC17641916VSP7102570 -
Lithostratigraphy
Lithostratigraphy Top depth [mMD RKB]Lithostrat. unit35854082682691410851230137816331633174717531905193120772134216322092209229323062432 -
Geochemical information
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Documents – reported by the production licence (period for duty of secrecy expired)
Documents – reported by the production licence (period for duty of secrecy expired) Document nameDocument formatDocument size [MB]pdf13.78pdf6.05pdf2.78pdf0.16pdf0.84pdf1.76pdf0.27pdf4.24 -
Drilling mud
Drilling mud Depth MD [m]Mud weight [g/cm3]Visc. [mPa.s]Yield point [Pa]Mud typeDate measured7601.1020.034.0WATER BASED22.10.19848201.1414.026.0WATER BASED22.10.198413581.2016.024.0WATER BASED22.10.198417641.1829.044.0WATER BASED31.10.198417821.1826.039.0WATER BASED01.11.198418301.1826.038.0WATER BASED02.11.198419171.2026.041.0WATER BASED05.11.198422571.1624.013.0WATER BASED08.11.198422571.1625.014.0WATER BASED09.11.198422571.1625.014.0WATER BASED09.11.198424361.1629.014.0WATER BASED12.11.198425581.1630.015.0WATER BASED13.11.1984 -
Palynological slides at the Norwegian Offshore Directorate
Palynological slides at the Norwegian Offshore Directorate Sample depthDepth unitSample typeLaboratory1765.0[m]COD1766.0[m]COD1768.0[m]COD1770.0[m]COD1775.0[m]COD1780.0[m]COD1785.0[m]COD1786.0[m]COD1800.0[m]COD1816.0[m]COD1825.5[m]COD1830.0[m]COD1837.1[m]COD1837.5[m]COD1839.5[m]COD1841.5[m]COD1843.5[m]COD1845.0[m]COD1849.5[m]COD1854.5[m]COD1856.0[m]COD1856.5[m]COD1863.2[m]COD1866.1[m]COD1879.0[m]COD1884.0[m]COD1885.0[m]COD1895.0[m]COD1896.0[m]COD1908.0[m]COD1910.0[m]COD -
Thin sections at the Norwegian Offshore Directorate
Thin sections at the Norwegian Offshore Directorate DepthUnit1971.00[m ]1907.00[m ]1907.00[m ]1904.00[m ]1902.00[m ]1901.00[m ]1900.00[m ]1896.00[m ]1892.00[m ]1892.00[m ]1891.00[m ]1889.00[m ]1887.00[m ]1886.00[m ]1877.00[m ]1872.00[m ]1870.00[m ]1870.00[m ]1869.00[m ]1856.00[m ]1845.00[m ]1843.00[m ]1841.00[m ]